An observer looks at the cell temperature in automotive battery packs

•A generic observer for LPV systems limiting the influence of measurement noise.•Battery diagnosis offered by internal resistance reconstruction for electric vehicle.•Polytopic observer, simple to implement, with experimental results.•Good quality of Li-ion battery cell temperature and internal resistance estimations.

The internal temperature of Li-ion batteries for electric or hybrid vehicles is an important factor influencing their ageing. Generally not measured, it can be reconstructed from an external measurement and a model. This paper presents the simplified modelling of heat transfers in a battery module, leading to a Linear Parameter-Varying (LPV) model. Then, a polytopic observer is proposed to estimate the cell temperature and internal resistance, ensuring a tradeoff between the convergence speed and the noise of the estimated states. Experimental results show the good quality of the estimation and the diagnosis potential offered by internal resistance reconstruction.